Fuel control for combustion apparatus



June 10, 1952 J. w. MILLER 2,600,123

FUEL CONTROL FOR COMBUSTION APPARATUS Filed NOV. 9, 1948' 2 SHEETSSHEET l INVENTOR. da/m 14/. 7/'// 9/" ATTORNEY June 10, 1952 J. W. MILLER 2,600,123

FUEL CONTROL FOR COMBUSTION APPARATUS Filed NOV. 9, 1948 2 SHEETS-Sl-IEET 2 Patented June 10, 1952 FUEL CONTROL FOR COMBUSTION APPARATUS John W. Miller, Lansing, Mich, assignor to Motor Wheel Corporation, Lansing, Mich, a corporation of Michigan Application November 9, 1948, Serial No. 59,068

Claims. 1

This invention relates to a fuel control for combustion apparatus and more particularly to a draft control oil feed for a vaporizing type oil burner.

In the operation of a vaporizing type oil burner, such as shown in the Valjean Patent 2,073,270, the heat outputof the burner is governed by the quantity of fuel supplied to the burner and increasespas the rate of delivery of fuel to the burner increases. For efiicient operation of the burner it is essential that the proper proportion of fuel and air are supplied to the burner under all operating conditions. Therefore, with this type of oil burner the heat output of the burner is increased by increasing the rate of deliveryof fuel to the burner and the heat output decreased by decreasing this rate. To obtain eificient combustion it is essential to adjust the rate of air feed to the burner every time the rateof fuel delivery is changed or vice versa. The rate of air delivery into the burner is governed by the draft and the draft is usually controlled by an automatic draft regulator located in the flue outlet from the combustion chamber of the apparatus. Such a draft regulator is shown in the Miller Patent 2,194,608. By adjusting such a draft regulator, the draft on the burner can be varied and consequently the rate of air delivery to the burner is correspondingly varied. It is to be understood that the draft can be the result of a natural chimney draft or can be a mechanical or induced draft.

This invention contemplates a liquid feed conarm which responds as the draft or rate of delivery of air to the burner changes to thereby maintain the proper proportion or mixture of air and vaporized fuel to obtain maximum comb tion efficiency. a

My invention contemplates a control for feed ing fuel to a burner wherein the heat output of the burner can be simply and easily changed by regulating the draft and the efficiency of the burner maintained. This object is accomplished by providing the liquid fuel control with a pres"- sure responsive device which responds to changes in pressure or draft in the burner to change the rate of liquid fuel delivery to the burner so that there is always maintained the proper proportion or relationship between the air and fuel fed to the burner to maintain efficient combustion. Thus, by a simple manual operation of regulating the draft to which the burner is subjected, the fuel fed to the burner is automatically and correspondingly regulated.

Fig. 1 is a side elevation of a conventional space heater embodying my invention.

Fig. 2 is an elevation partly in section showing the oil control unit.

Referring more particularly to the drawings there is shown a conventional space heater, generally designated l, comprising a vaporizing type fuel burner 2 and combustion chamber 3 which is connected to the chimney or stack by pipe or flue 4. This type of vaporizing oil'burner is conventional and is similar to the one shown in the Valjean Patent 2,073,270.

Flue 4 is provided with an adjustable draft control regulator 5, preferably such as shown in the Miller Patent 2,194,608. Automatic draft regulator 5 comprises a pivoted blade {5 having an adjustable knob i thereon to which a weight is attached. The draft on the burner can be varied by rotating the knob "i to admit more or less air to the flue outlet through the draft regulator. The draft regulator when once set maintains a substantially constant draft on the burner 2. Since automate draft regulator v5 is shown by way of description to illustrate one regulator for automatically controlling the draft on the burner, for further details on the manner of operation of this regulator reference may be had to the said Miller patent. Draft regulator 5 admits air from the space being heated into the flue 4 andtherefore the full chimney draft is not applied to the burner but the desired draft is applied to burner 2. Any other draft control apparatus which can be adjusted to control the draft could be substituted for the regulator shown and described.

An oil control, generally designated 8, is mounted on the apparatus in correct relation to the burner and is shown more in detail inFi-g. 2. Oil is supplied from a tank or other sourcelnot shown) to control 8 through pipe line 9 which communicates with passageway H] in fuel control housing II. Liquid fuel, such as oil, passes from passageway IE) through port l2 into float chamber I 3. Port I2 is controlled by valve I lwhich is biased upwardly by compression spring l5 which acts between shoulder 16 on valve 14 and shoume I7 on the valve housing. Float I8 is fixed to lever 21 which is pivoted as'a-t I9 on bracket'zil within float chamber 13. One end 22' of lever 21 contacts-shoulder 1.5 of valve M. The lower.

end of pin 23 contacts the upper end of valve 14 and extends upwardly through the top of float chamber housing I! where it contacts lever 24. Lever 2e is pivoted atone end to bracket 2:) as at 25. The other end of lever 24 contacts the lower end of pin 25 which is affixed to flexible diaphragm 27 as at 28. Pin 2.6 is guided inbushing .29 which is fixed on bracket 31!. Bracket 39 is supported on the top of housing I I. Bushing 29, which is adjustable on bracket 33, supports servo-motor 3| which takes the form of flexible diaphragm 21, housing 32, suction chamber 33 and chamber 34 which is at all times in communication with atmosphere through openings 35. A small opening 48 is provided in the diaphragm 21, the purpose of which Will'appear later. If desired, a compression coil spring can be mounted in suction chamber 33 biasing diaphragm 2's downwardly but such spring is not essential.

Suction chamber 33 communicates by means of conduit or pipe line 36 with pipe lines 3'! and 38. Pipe line 38 communicates with float chamber 13 and oil is fed through lines 38, 31 into the lower end or upon the bottom 39 of burner 2. Pipe line 38 communicates with outlet 4!! in housing ll. Outlet 40 is controlled in a conventional manner by valve 4!. Valve 4| can be manually adjusted by knob 42 in a conventional manner and when thus manually adjusted remains in this set position to thereby control the maximum fuel flow at that position from float. chamber l3 through lines 38 and 3! to the burner. Float I8 is biased downwardly not only by spring 15 but also by weight 43 which is mounted on float [8.

The operation of my device is as follows: knob 42 will be turned to adjust valve 4| to a fixed position to thereby control the maximum rate of flow of fuel from float chamber l3 through lines 38 and 31 to burner 2.. Knob T on draft regulator will be turned to adjust the draft depending upon whether more orless heat is desired. Assuming that a minimum of heat output is desired from the burner, then regulator 5 will be adjusted to reduce the draft on burner 2. The draft on burner 2, that is, the pressure obtaining in burner 2, will also obtain in suction chamber 33 because chamber 33 is in communication with the inside of burner 2 through lines 31 and 36. Since regulator 5 is set for low draft, the pressure in chamber 33 will be slightly below atmospheric, for example, .02 inch of water (water draft gauge reading) As shown in Fig. 2, the fuel control is set for low oil feed and low draft. At this time the level of the liquid fuel in chamber 53 will be at line- 45. Under such low draft diaphragm 21 will act through pin 26 and lever 24 to exert a downward pressure on pin 23 and valve I4. This pressure is sufi'icient to close valve I4 when the float I8 is buoyed upwardly by the oil at the level indicated at 45. This oil level is about onesixteenth of an inch above the level of the outlet opening 40. This is the required conditionfor feeding a small amount of oil to the burner to ive a low fire.

To obtain a higher fire the draft regulator 5 is adjusted to produce more draft on burner 2 and diaphragm 21. For example, if the draft regulator is adjusted to increase the draft on the burner to .07 inch of water, then there will be a drop of pressure in chamber 33 which will cause diaphragm 21 to flex upwardly or to rise and in turn allow lever 24 to rise and thereby take some of the bias or pressure off spring 46 which biases lever 24 upwardly. The effect of this is to decrease the pressure on valve I4 caused by lever 24. As the pressure exerted by lever 24 on valve I4 decreases, valve I4 opens, admits liquid fuel through port 12 into chamber [3 thereby causing the liquid fuel level to rise to the level indicated by line 41. As the liquid level rises the pressure exerted by float l8 through lever arm 22 on valve l4 increases so that an equalized condition is soon reached. The oil outlet valve 4| is so proportioned that the amount of oil necessary to provide a low fire is obtained when the oil level is at and the oil necessary to provide a high fire is obtained when the oil level is at 41. Intermediate fires are obtained by oil levels between these two extremes.

From the above it is evident that I have produced a draft responsive oil feed control which will feed the proper amount of oil to a fuel burner as the draft on the burner is changed to maintain efficient and complete burning of the fuel. As the draft is changed the oil flow will be automatically changed. This oil flow change is the result of a change of level of the oil in the control which feeds the oil to the burner. This change of level in the oil control is in turn caused by changing the bias on the oil valve feeding oil to the control. The oil level in the control is determined by a float in the oil chamber. The diaphragm which responds to changes in draft changes the bias on the oil inlet valve, which change in bias alters the effective buoyancy of the float. As the effective buoyancy of the float is changed a different constant oil level is obtained in the control chamber H corresponding to the draft in the burner as determined by the setting of the automatic draft regulator. The variable feed of oil to the burner is determined by the change of oil level in the oil control.

It is, of course, understood that the liquid fuel or oil flows by gravity from chamber 14 through lines 38 and 31 into burner 2.

Under normal operating conditions pipe 31 s will not be completely filled with oil, but if in any case control 8 should feed an excessive amount of oil so that burner 2 is flooded and oil completely fills pipe 31, then communication between chamber-33 and burner 2 would be shut off and diaphragm 21 would not be further influenced by changes of pressure in burner 2 until the oil in pipe 31 receded to the point where pipe 31. would not be completely filled and communication would again be established between chamber 33 and burner 2. If the flooded condition of burner 2 was extreme so that liquid fuel level would rise upwardly in pipe 36, then the pressure in chamber 33 would become atmospheric causing diaphragm 21 to move downwardly and act through pin 26, lever 24 and pin 23 to bias valve l4 downwardly or toward closed position. This downward movement of the diaphragm 27 occurs when line 31 is completely'filled with oil since at this time the draft operating on the burner cannot reach the chamber 33. When this occurs there is a leakage of air through the small hole 48 in the diaphragm allowing the pressure above the diaphragm in chamber 33 to become atmospheric. The diaphragm thus moves downward to stop the oil feed. Leakage of air through opening 48 is so small that under normal operating conditions its effect is negligible; This is true because as has been explained .02 inch draft gives an oil level indicated at 45. When the draft becomes zero the level is lowered to a level to stop the oil feed.

I claim:

1. Combustion apparatus comprising a liquid fuel burner, a combustion chamber communicating therewith and having a flue outlet, means for varying the draft on the burner including an adjustable draft regulator associated with the flue outlet, means for supplying fuel to the burner in regulatable quantities including a fuel chamber having a fuel inlet, a fuel outlet to the burner, said fuel outlet being arranged such that the rate of feed of fuel to said burner varies in accordance with the level-cf fuel in said fuel chamber, :a' valvefor controlfingthe admission of fuel through said inletjntotthe chambnand mechanism for controlling the, opening and closing of theisaidvalveto changeithe level of fuel in the chamber in .accordancewith the change in the draft on the burner, said mechanism comprising a servomotor responsive to changes of draft in said burner, means operatively connecting said servomotor with said valve such that the servomotor responds to the pressure in said burner to close said valve at levels of fuel in said chamber, the heights of which vary inversely with the pressure in said burner throughout a range of operating pressures, whereby the rate of feed to said burner through said outlet is increased as the pressure in said burner decreases.

2. Combustion apparatus as claimed in claim 1 wherein said mechanism includes resilient means for normally biasing said inlet valve toward open position, and means responsive to the level of fuel in said chamber for biasing said inlet valve toward closed position whenever the fuel reaches or exceeds a predetermined level.

3. Combustion apparatus as claimed in claim 2 wherein the liquid level responsive means comprises a float and level, the buoyancy of the float as the liquid level rises acting through said lever to bias said inlet valve toward closed position.

4. Combustion apparatus as claimed in claim 3 wherein the connection between the servomotor and valve includes a lever for transmitting the force of said servomotor to said inlet valve upon a rise in pressure in the suction chamber of the servomotor.

5. The combination set forth in claim 3 .wherein said servomotor is arranged to increase and decrease the effective buoyancy of said float in response to a rise and fall respectively of the pressure in said burner throughout the range of operating pressures.

6. Combustion apparatus comprising a liquid fuel burner, a combustion chamber communicating therewith and having a flue outlet, means for varying the draft on the burner including an adjustable draft regulator associated with the flue outlet, a source of liquid fuel, a chamber having an inlet and an outlet, a conduit connecting said outlet to the burner, said outlet being arranged such that the flow of fuel to said burner through said outlet varies in accordance with the level of fuel in said chamber, a valve for said inlet for controlling the rate of flow of fuel from said source into said chamber, and mechanism for controling the opening and closing of the inlet valve to change the level of fuel in the chamber in accordance with the change in draft on the burner, said mechanism comprising a servomotor responsive to changes of draft on said burner, means operatively connecting said servomotor with said inlet valve such that the valve is opened to raise the level of fuel in said chamber when the draft is increased and closed to lower the level of fuel in said chamber when the draft is decreased, whereby the level of fuel in said chamber varies directly with the amount of dra t throughout the range of draft operation of the burner.

7 The combination set forth in claim 6 wherein said mechanism includes resilient means bias ing said valve toward open position, and means responsive to the level of fuel in said chamber for biasing said valve toward closed. position.

-8. The combination set forth in=clalm '7 wherein "said fuel level =-res-ponsive means comprises a float 'operatively connected with said valve to bias said valve toward closed position as the level of fuel in said chamber rises, said servomotor being arranged to progressively decrease the buoyancy of said float in response to a progressive decline in the draft on said burner.

9. Combustion apparatus comprising a liquid fuel burner, a combustion chamber communicating therewith and having a flue outlet, means for varying the draft on the burner including an adjustable draft regulator associated with the flue outlet, means for supplying fuel to the burner in regulatable quantities including a fuel chamber having a fuel inlet, a fuel outlet to the burner, said fuel outlet being arranged such that the rate of feed of fuel to said burner varies in accordance with the level of fuel in said fuel chamber, a valve for controlling the admission of fuel through said inlet into the chamber, a float responsive to the level of fuel in said chamber to open and close said valve, said float being arranged to close said valve when the fuel within the chamber reaches or exceeds a predetermined level, resilient means biasing said valve toward open position, and a servomotor responsive to the change of draft on said burner and operatively connected with said valve, said servomotor being arranged to decrease the bias of said resilient means and thereby increase the effective buoyancy of said float upon a rise in pressure in said burner and to increase the bias of said resilient means and thereby decrease the effective buoyancy of said float upon a fall in pressure in said burner, whereby a fall or rise in draft on said burner produces a corresponding fall or rise in the height of the fuel'level in said chamber to vary the flow of fuel to said burner in accordance with the draft on said burner.

10. Combustion apparatus comprising a liquid fuel burner, a combustion chamber communicating therewith and having a flue outlet, means for varying the draft on the burner including an adjustable draft regulator associated with the flue outlet, means for supplying fuel to the burner in regulatable quantities including a fuel chamber having a fuel inlet, a fuel outlet to the burner, said fuel outlet being arranged such that the rate of feed of fuel to said burner varies in accordance with the level of fuel in said fuelchamber, a valve for controlling the admission of fuel through said inlet into the chamber, a float responsive to the level of fuel in said chamber to open and close said valve and thereby control the height of the level of fuel in said chamber, and means for increasing and decreasing the buoyancy of said float in response to a rise and fall, respectively, in the pressure obtaining in said burner, whereby the level of fuel in said chamber varies inversely with the pressure in said burner throughout the pressure range of operation of the burner, said last mentioned means comprising a servomotor responsive to changes in pressure in said burner, and means operatively connecting said servomotor with said valve, and including resilient means acting on said valve in opposition to said float to bias said valve to open position, said servomotor being arranged to increase the bias of said resilient means and thereby decrease the effective buoyancy of said float in response to a fall in pressure in said burner and to lessen the bias of said resilient means and there- JOHN W. MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

Number 8 UNITED STATES PATENTS Name Date Holland Sept. 27, 1921 Coultas June 6, 1922 Sheer Oct. 1'7, 1922 U'llstrand Aug. 19, 1941 Miller- Nov. 21, 1944 Martin Jan. 9, 1945 

